Salts Abbreviation HBD Molar ratio Symbol Methyltriphenylphosphonium bromide MTPB TEG 1:4 DES1[13] Methyltriphenylphosphonium bromide MTPB DEG 1:4 DES2 Methyltriphenylphosphonium bromide MTPB EG 1:4 DES3 Methyltriphenylphosphonium bromide MTPB GL 1:4 DES4

Table 1: Composition and abbreviation of DESs used in this research.